1. Field of the Invention
The present invention relates to a liquid crystal display device, in particular, a data-line driving circuit included in a liquid crystal display device.
2. Description of the Related Art
A liquid crystal display device uses a potential difference between a pixel electrode and a common electrode that are included in each of the pixel circuits to control a transmittance of liquid crystal. In the case where a time average of a potential applied to a pixel electrode of any one of the pixel circuits deviates from a common potential applied to the common electrode (this case is referred to as the application of a DC component to the liquid crystal), the relation between the transmittance of the liquid crystal and the potential difference is not maintained any more to result in the generation of a ghost image. In the liquid crystal display device, polarity of the potential applied to the pixel electrode changes for each frame to prevent the generation of the ghost image. The polarity indicates that the potential applied to the pixel electrode or a data line is higher or lower than the common potential. A positive-polarity potential indicates that the potential is higher than the common potential, whereas a negative-polarity potential indicates that the potential is lower than the common potential.
Even when an average of the positive-polarity potential and the negative-polarity potential applied to the data line for a certain level of grayscale is equal to the common potential, the ghost image is disadvantageously generated in some cases. This is because the average of the positive-polarity potential and the negative-polarity potential applied to the pixel electrode differs from the common potential in this case. Therefore, conventionally, control for shifting the average of the positive-polarity potential and the negative-polarity potential applied to the data line from the common potential by a predetermined value is performed.
Japanese Patent No. 3704716 discloses a liquid crystal display device for shifting positive-polarity and negative-polarity precharge potentials applied to a data line from a central potential of a data voltage amplitude by a predetermined value. Japanese Patent Application Laid-open No. 2004-219824 discloses a liquid crystal display device for controlling whether or not to perform precharging for a pixel circuit in accordance with a temperature.